The Human Visual Claustrum Responses to Physical Stimulus Properties and Subjective Content During Movie Viewing.

The human claustrum is a small bilateral grey matter structure that is highly interconnected with cortical and subcortical regions. It has been implicated in different functions including sleep, multisensory integration, consciousness and attention, yet its exact function remains unclear. The primate claustrum is known to have distinct sensory regions, with the visual zone recently demonstrated in humans using high-resolution fMRI. In this study, we investigated stimulus properties that drive human visual claustrum activity. First, we tested the association of its response with various low- and mid-level physical stimulus features, including temporal and spatial contrast, color and motion. Second, we tested the association with subjective ratings of arousal, valence and interest. To compare the claustrum's responses with visual cortical regions, we performed the same analysis with the hV4 and hMT/V5+ complex. We found that the claustrum's visual response was associated with motion, as well as with arousal, interest and valence. The pattern of claustrum responses was similar to hMT/V5+. Given the well-established link between arousal and attentional allocation, as well as between saliency and motion, our results suggest that the visual claustrum may contribute to saliency detection and attention modulation during the sensory input.